Currently, one in eight women is at risk of contracting breast cancer in her lifetime. A significant proportion of breast cancer patients develop advanced or metastatic breast cancers that are frequently resistant to conventional anti-cancer therapy and incurable. The current proposal is aimed at the development of anti- cancer agents inhibiting cancer progression, formation of metastases and resistance to conventional therapy. Breast tumors express high levels of TGF-? and active NF-kB that promote metastases and resistance to therapy. TAK1 (TGF-beta-activated kinase 1) mediates the pro-oncogenic activities of the TGF-?-NFkB axis in cancer, activating molecular pathways contributing to aggressive breast cancers, such as ER-negative and HER2-positive cancers, that are difficult to treat with present therapies. We developed synthetic compounds that inhibit oncogenic activities of the TAK1-NFkB axis but do not block the tumor-suppressor function of TGF- ?. These agents were identified in the screen of a focused library of novel synthetic compounds mimicking the key structural elements of the relatively complex natural product 5Z-7-oxozeaenol, a potent inhibitor of TAK1. Two compounds, HDAB001 and HDAB006, exhibited the most promising properties and will be used for further optimization as drug candidates. HDAB001 decreased the growth of human breast carcinoma xenografts in a mouse pre-clinical model without noticeable side effects such as distress or weight loss. The proposal is aimed at improving the efficacy and pharmacological properties of the identified lead compounds. We will generate and test focused chemical libraries around the lead compounds. The most promising compounds will be examined alone or with current anti-cancer agents in preclinical mouse models. Specific Aim 1 will optimize the efficacy and pharmacological properties of the identified lead compounds. The focused chemical library design and synthesis will be performed by Prof. Huw Davies' group, Chemistry Department, Emory University, and will follow strict guidelines for lead and drug candidates. The Davies group will use novel synthetic strategies for chemical synthesis of novel compounds. Aim 2 will examine the functional activity of focused chemical libraries in in vitro and in vivo pre-clinical breast carcinoma models. The Bakin group at RPCI will perform biological testing of the synthetic compounds, interrogating major drug properties (potency, selectivity, targets) and mechanism of action. The collaboration between the Davies and Bakin groups is essential for the overall success of the project. If successful, the study will provide a novel class of anticancer agents with superior pharmacological properties over present agents and could be used alone or in combination with conventional therapy for treatment of advanced breast cancers. The most promising compounds will be available for immediate development of Phase I clinical trials as mono-therapy or in combination with conventional agents.